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The observed response to selection leads to an estimate of the narrow-sense heritability (called realized heritability). This is the principle underlying artificial selection or breeding. Example
Broad-sense heritability, H 2 = V G /V P, Involves the proportion of phenotypic variation due to the effects of additive, dominance, and epistatic variance. Narrow-sense heritability, h 2 = V A /V P, refers to the proportion of phenotypic variation that is due to additive genetic values (V A). [6]
Heritability is the proportion of variance caused by genetic factors of a specific trait in a population. [1] Falconer's formula is a mathematical formula that is used in twin studies to estimate the relative contribution of genetic vs. environmental factors to variation in a particular trait (that is, the heritability of the trait) based on ...
Narrow sense Heritability (h 2 or H N) focuses specifically on the ratio of additive variance (V A) to total phenotypic variance (V P), or: h 2 = V A / V P.. In the study of Heritability, Additive genetic effects are of particular interest in the fields of Conservation, and Artificial selection.
Narrow-sense heritability has been used also for predicting generally the results of artificial selection. In the latter case, however, the broadsense heritability may be more appropriate, as the whole attribute is being altered: not just adaptive capacity. Generally, advance from selection is more rapid the higher the heritability.
GCTA estimates are likewise sometimes misinterpreted as "lower bounds" on the narrow-sense heritability but this is also incorrect: first because GCTA estimates can be biased (including biased upwards) if the model assumptions are violated, and second because, by definition (and when model assumptions are met), GCTA can provide an unbiased ...
The degree to which an organism's genes contribute to a complex trait is called heritability. [53] Measurement of the heritability of a trait is relative—in a more variable environment, the environment has a bigger influence on the total variation of the trait. For example, human height is a trait with complex causes.
Intuitively, SNP heritability increases to the degree that phenotypic similarity is predicted by genetic similarity at measured SNPs, and is expected to be lower than the true narrow-sense heritability to the degree that measured SNPs fail to tag (typically rare) causal variants. [50]